Chemical pulp-cooking process



Patented June 2.9,` 1926..`r

UNITED STTA J.erl'y control-the cooking operation` e PATENT OFFCEV* YGEORGE s1VoLA,-onnnxfrn, NEW nomi.

CHEMICALPULP-COOKING PROCESS.

This inifentionrelfitestoe nen7E method'of testingpulp troni tiinetotime during the cooking operationlto Yenable-'the vcook to propf end'Valso tlieblw'ing point', es more fully hereinafterj setiorth".V I j,

"l In the` methods `at present` in use, the" cook keeps" theteinpereturei and pressure' Within oetrln4 limitsl which die adaptedlto' eaeliini dividul ,Inilll He "draws samples' of Vthe 'liquor from'tiinetoftimeA and analyses the j same ifm? total, d -ff'ee and Combined'SO2 a it,E and notesv its appearance; lthen'.v

isfli-berlited ffiointhe 'liizjnin'v by ycoloration of Athe j liquoilFioni these facts he makes his deduetio'nv Iand vope'rttcs'the'dig'estei" ,aCQCQrdingly.v The princifpal'inethods Of'pdeterniiniingthe blowing point, i. ethe tiinewhen the cooking is'cojrnplfeted, are

test atodeterrnine./tlioglincunt of'liine present et the letter pziijtffv'the cook-ing,Y lensingv theVV blowing". point on tliefheight al'nd'appearance of the precipittend elsoon the ycolo'rl and sniell-oftheliquori.; -Y

' out L i Y A in'ethods'- for coo-king? controlling fand testV They'7Vary in different inills-dependinv' the composition 'of ythe acid;third,V the personal ideas of the nienin charge. Thus,the blowing. pointof theV digestenby Leith :pieseneeof so inany Variablefactors, all of lwhich inore 'orless' affect the product rofthe sulphiteprocessyntheblowing oi' two i digesters consecutively eigeedierent inregard to bleagzh :consumptionand other qualities the cookin'gseldoni ntien-obtained (bi-)They :areebaseflfmwfe L01 ',(strength, orvinstance)because: (a) The predetermined standards at certain stagesuof agree withYthejA producy H draws oit.` n, i 'portion oftlfiecookingf-liquorgtests:ortotnl SO2,4 and' blows the digester :it:Veer-tain 5 0l 7', dfnc'lsm'fel'l teszQ-Th'e cjoolrtkes asinple ofthe`liquor, smells itgandI tests the colon lof* Vthe *liquor again'stf apredeter- -n`ii.ned'color st'emd'ard-y and when lie-"finds y p v a"tiesto-#The @ook takesV a sample of tlielicpior,V in alrese'rninonialined-Verbo*e;v there s-reiio sten'dard color,' smell," etc.,testsjismone or less,- guess: Work, 1 as they tellvnothingaboutthequelitjlofF the Vpulp.Whichfis,about to beblown.'VA In the lessl'on tlieliquor and Ynot 4onfthe lfullplitseli. lt'ls. thefobjeotof myinventionto substi- Vtutefor these indefinite Weysofcontrolling the,cooking and? determining of the correct blowing pointe prooess'rtliiehWill elim' nate indeiniteriess bybeingvi based on the quality oftlie'rpulp itself. y My process is ,based on the following facts :KVVhena given Weight of pulp v(which is taken out ofthe digeste'runder.pressure'during the cooking period) V4is added. to nl definite'Volume'A of inangana'te by the ,Y incrustiiig, rnattersfy re# greeV ofdisintegrationoff cellulose; the

quickness or' the' reaction? furnishing Ineas- V ure ot theldelignilicetron ofthe pulp that cani-be expressed in seconds.

My test-s arefi adefrom'timey to tii'rne,y eey potassiumVpernfiengnettea` (KrnnOQ solution Y which is acidied fWith, sulphuricacid (tiSOi-bthe,'rete-Oebsorptonoftheperf 70 mailling'jin the'pulp`correispvondi-i totliefdef n' half hour orfoneho'ur iigpfilrt, and foreach i test I proceed sjlrollors; Takeesamplefof 2,00 to- 300.vccigfrtheii eClClifyrit Withif ec.` imrinal4 sulphuric acid(ll2SQn/l).Y temperature? of y'pernien'ganate .seine for erich test, forfex'anipld25 C,"

leap Y u sample' of thejpulp, Weslied end'disintegrnt- `ed 'asdescribed, in'one` hand; rvstartl stop f zttch; droptlie pulpfint'o thesolution.; put

':stopper y1n t'ubeor flask; Vstaart 'shaking :gen-

tly and regularly, .et the, seine .tune observ-` ingtlie color of theVSolutionI by; the @7,33

when Color vchangesy :from initiajlcolor, oletf; to. v.yellow (oryellowish vbjrown) stop, the, Watch; noter infseconds the time required;to 'decolorizethev solution.

As soon` esthe pulp becoin'es soft .enough to disintegrate ythe chipsiasstated, I4 start teste ing by using-fthepjiioregoingmethod;V I makeythese tests `:itintervals' ofhalfgzinl'hour or Y 'an'houigY anfd'liee'parecord of each temperalturens ,Well as yofeach-acidtest. vIdecide auniform` rate of increasef ingtempereturefto decide which kind et' acidmost economically lproduces the desi 1ed quality oit pulp. I also Acid.vPulp test.

Y Total S05 Seconds at per cent. C'.

' The manner of using the foregoing table `will be obvious from thefollowing example:

' It the totalSOzwere 0.54% and the pulp at j the same time were 13,Where it should be at least l5, this would show that the cookingprocess'was not goingY correctly.A In other words,.it is relieving tfoomuch. So, by keeping close watch ofthe stock and'acid test and observingthe table, the cooking process can beV corrected accordingly.

*l/Vhen, the stock test .shows that it has reached thepoint required togive the specified-kind of pulp, the digester is ready to be blown.. As`far -as'the weight of pulp, and proportions of sulphu-ricacid andpotassium permanganate' are concerned, there are no definite ratios;they may vary indefinitely. For example, same weight of pulp, sameVolume of potassium permanganata and greater volume of sulphuricacidwould give different results than shown in the table, but the stockwouldbe of the same hardness.

factV that myftests are based on the pulp itseli` and not on the liquor,guess work is eliminated. It also makes it possible to pro# duce anydesired quality of pulpby work` `ing out a table and observingit, aspreviously described.-V It also makes itpossible toY know the exactVtime to blow olia the dil 'Y gester. Also, it makes it possible toproduce pulp which is practically uniform in hard-V ness, strength,color, etc., this being one of the most important advantages of mvmethod. n

My method also enables me to obtain the VVhighest yield by'avoidingovercooking and knowing the exact blowing point. I also economize insulphur consumption by rea@ son of the high yieldand because of the factthat I may'k determine the most economical y composition of acid, itbeing known that the higher the blowing Vtest for'the acid, the greaterthe lessor" sulphur. The higher yield of the higher yield, saving oftime.

K noting thetime required for and the avoidance oit overcooking andtheblowine` atthe exactl ro er oint enable C3 Y me kalso to produce lowersteam consumption.

.My method also vis'time-saving in'that the softer pulpV I cook, lthelonger timeV it takes;

tor example, if Vhard pulp vis desired, in-

stead I get soft pulp lunder'the'lpresent methods, thus wasting the timethat was Y taken from the period when the pulp was or" Y the desiredquality. It Vnecessarily Vfollows thaty I get increase of productionbyreasor It Wil be understood that for each particularpur'v procedure.For eXample,"if 'I am cooking easy bleaching pulp, Iy can determinethecorrect hardness and thus balance the yield, sulphur, 'steam'.consumption, time, etc., against the cost of bleaching, loss of yield,etc. It will also be Vobvious that my method is not confined to use ofthe chemicals menposefI can'determine the most economical 'tioned above,but can be carried. out with` any chemicals which may be used for deter-Y mining the degree of disintegration of the pulp sample in theabove-described -Way, during the cooking pulpy process. Y

'What I claim as new is:

l. In chemical pulp cooking, the process (of ascertaining the progressofthe cooking" operation, consisting in removing from the as period in anychemical cooking mass a portion of the mass,l sub-vV jecting a givenweight ot thisk separatedk pulp to the action of a delinite volume `of avchemical solution capable' oi reacting' thereon in such manner as tocause'a change in color of the solution, and yobservingand reaction totake place. I Y 2. vIn chemical pulp cooking, the process ofascertaining the progress `ot the cooking operation, consisting inremoving a portion of the pulp duringfthe cooking operation, Y washingand disintegrating the pulp and re- Y It will be observed that by reasonof the r moving the rtree water'therefrom, taking .a delinite weightoflthis washed and disintegrated pulp and subjecting the same to theaction of a'given volume ot' a chemical solusuch chemical tion capableof react-ingv on the pulp to i change thecolor of the solution,and'noting'V the time requiredY for suchchange of color to take place. In. 1

- 3;' In sulphite pulp cooking, the process Vof ascertainingrtheprogress of the cooking yoperation, consisting in removing a part of thecookingjliquor and `testing the same for total SO2, removing a part ofthe'pulp at o'l" this pulp tothe action of aV definite volume jot a'chemical solution/capable ofabsorption by the incrusting mattersremaining` in the fthe same time yand subjecting a given weightV y i.fing a Ineasure 'of the delignifieation of the pulp that can beexpressed 1n seconds.V

4. V'In chemical pulpY cooking, the process ,of ascertaining` theprogress of the Cooking .p operation, consisting inremoving 'ya portion'of the pulp, disintegra-tng Aand washing the v pulp, taking a givenWeight of this'washed pulp separated from its free Water and subjectingit t0 the ehemioalaction ofr a j l0 definite Volume of potassiumpermanganate of the permanga-nate by the inerusting mat- Y i' tersremaining inthe pulpthis rate of alo-l sorption `being; 'an index lofthe degree of disintegration ofv the cellulose.Y

In testimony whereof I signature.

hereuntoefliic f Y f Y :GEORGE sivomny 'n

